How will Venter’s scheme work?In short, he wants to send machinery to Mars that can robotically sift through Martian soil to isolate any microbes it contains, sequence their DNA and then beam the digitised results back to Earth. These would be used to create a synthetic version of the Martian genome, which could then be used to recreate Martian life on Earth – all without having to deal with the difficulties of actually bringing the sample back.

How far along are the plans?Venter has been scooping DNA from seawater for a number of years, with some interesting results. At Wired Health, he said that similar technologies are beginning to be tested at a Mars-like site in the Mojave Desert in California, as a prelude to a Martian mission. The next planned landing is NASA’s InSight mission, scheduled to launch in 2016.

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Assuming we can get a gene sequencer to Mars, what are the chances that it will discover life in the soil?Venter is unequivocal&colon; “There will be DNA life forms there,” he said at the conference. NASA’s 1976 Viking mission failed to find any evidence that there are or ever were – but some dispute that. Even if Mars’ surface is barren, though, recent surprising discoveries of life deep below Earth’s surface – some of it apparently surviving independently of the sun’s energy – suggest that Mars’s rocky interior might contain life.

Venter is certain that subsurface is the best place to seek DNA on Mars&colon; “Life discovery will have to wait until we can drill beyond the surface.” On Earth, life goes a long way down – to at least 3.6 kilometres.

What about past life?This month’s discovery of an ancient riverbed on Mars has certainly got astrobiologists excited. The find, by NASA’s Curiosity rover, suggests habitable environments once existed on the planet. However, the river probably dried up several billion years ago, according to the Curiosity team – too long for any DNA from that era to have survived.

Earlier this month, biologists established that DNA has a half-life – it breaks down at a roughly predictable rate. Even if conditions are ideal for its preservation, measurable quantities should all but have disappeared 1.5 million years after an organism’s death.

So are extinct Martians out of the hunt?No. A team at the Massachusetts Institute of Technology is also building a sequencer called SETG (Search for Extraterrestrial Genomes), that will search for DNA or RNA from past or present life. “We’d be looking for something that’s alive or recently dead,” says team member Chris Carr – although he is using “recently” in the geological sense, so could go back as far as a million years. The team has been working on the device for about seven years.

The current incarnation uses a chip built by the company Ion Torrent . The team is already testing parts of SETG in the field. They have brought it to an active volcano in Argentina that is chemically similar to Mars, and they plan to return there in January.

Might DNA survive longer on Mars than on Earth?It’s possible, says Morten Allentoft at the University of Copenhagen, Denmark, who led the DNA half-life study. Conditions on Mars are very different from those on Earth, he says. The surface of Mars is bombarded with radiation, for instance, which could accelerate the break down of DNA in Martian soil. “However, with its dry and cold environment, one could speculate that post-mortem DNA would generally last longer on Mars than on Earth.”

Allentoft’s team found that DNA decay rates accelerate in the presence of water and oxygen, so the apparent absence of both from the surface of Mars – at least in the recent past – could be a bonus for Venter’s DNA hunt. “It really is just speculation though,” Allentoft cautions.

There’s bad news too. The assumption is that Martian life is, or was, microbial. “Any Martian DNA would not be preserved inside hard tissue but in small cells or as fragments of free DNA,” says Allentoft. Without the protective environment provided by bone or teeth, DNA degrades much faster, he says.

Is Venter a visionary?“He seems to be very certain that there’s DNA there,” says Carr. “That’s actually really concerning to me–I think there’s a good case for why we would do this, but it makes the effort seem more ‘fringe’ by having certainty.” He adds&colon; “We think there’s a good chance that it’s there, and I definitely think we should be looking for it.”